3Com 4.2.2 manual Lecs

LAN Emulation

Configuration Server

(LECS)

An Introduction to ATM and VLAN Management Basics C-9

emulated Ethernet service interface to higher level software which implements the LAN Emulation User-to-Network Interface (LUNI).

The LAN Emulation Configuration Server implements the assignment of individual LAN Emulation Clients to different emulated LANs. When a LEC initializes, it establishes connection to the LECS. Based on its own policies, configuration database and information provided by clients, the LECS assigns any client which requests configuration information to a particular emulated LAN service by giving the client the LES’s ATM address. This method supports the ability to assign a client to an emulated LAN based on either the physical location (ATM address) or the identity of a LAN destination which it is representing (ELAN name).

LAN Emulation Server (LES)

The LAN Emulation Server implements the control coordination function for the emulated LAN. The LAN Emulation Server provides a facility for registering and resolving MAC addresses to ATM addresses. Clients may register the LAN destinations they represent with the LAN Emulation Server. A client will also query the LAN Emulation Server when the client wishes to resolve a MAC address and/or route descriptors to an ATM address in a process called LE Address Resolution Protocol (LE_ARP). The LAN Emulation Server will either respond directly to the client or forward the query to other clients and then forward the client response. In an SVC environment, the LES responds directly to the LE_ARP to enable an LEC to locate the BUS.

Broadcast and

Unknown Server

(BUS)

The Broadcast and Unknown Server handles the following:

■Data sent by a LAN Emulation Client to the broadcast MAC address.

■All multicast traffic.

■Initial frames which are sent by a LAN Emulation Client before the data direct virtual channel to the ATM address has been resolved.

All broadcast, multicast and unknown traffic to and from a LAN Emulation Client passes through a single BUS.

The BUS also handles ATM connections and manages its distribution group.

Virtual Channel	Figure B-1Communication among LAN Emulation Clients and between LAN
Connections (VCC)	Emulation Clients and the LAN Emulation Service is performed over ATM Virtual
	Channel Connections (VCCs). Each LAN Emulation Client must communicate
	with the LAN Emulation Service over control and data VCCs. Emulated LANs